CVE-2017-17757 in TL-WVR
Summary
by MITRE
TP-Link TL-WVR and TL-WAR devices allow remote authenticated users to execute arbitrary commands via shell metacharacters in the interface field of an admin/wportal command to cgi-bin/luci, related to the get_device_byif function in /usr/lib/lua/luci/controller/admin/wportal.lua in uhttpd.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 12/16/2019
This vulnerability exists in TP-Link TL-WVR and TL-WAR wireless router devices running uhttpd web server software. The flaw resides in the admin/wportal command handler within the cgi-bin/luci interface, specifically in the get_device_byif function located at /usr/lib/lua/luci/controller/admin/wportal.lua. The vulnerability stems from insufficient input validation and sanitization of user-supplied data passed through the interface field parameter. When authenticated users submit maliciously crafted shell metacharacters through this interface field, the system fails to properly escape or filter these characters before processing them as part of command execution. This creates a command injection vulnerability that allows remote authenticated attackers to execute arbitrary system commands with the privileges of the web server process. The affected devices are particularly vulnerable because they use uhttpd as their web server, which is commonly employed in embedded networking devices and is susceptible to such injection flaws when proper input sanitization is not implemented. The vulnerability is categorized under CWE-78 as "Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')", which represents one of the most critical classes of vulnerabilities in web applications and network devices.
The operational impact of this vulnerability is significant as it provides attackers who have already gained authentication credentials to the device with full system-level command execution capabilities. This means that an authenticated attacker can perform actions such as modifying device configuration files, accessing sensitive data, installing malware, creating backdoors, or even compromising the entire network infrastructure controlled by the affected router. The attack vector is particularly concerning because it requires only authentication, which is often obtained through default credentials, weak password policies, or social engineering attacks. The vulnerability affects the administrative interface of these devices, which typically have elevated privileges and can control core network functions including firewall rules, routing configurations, and user access controls. From an attack framework perspective, this vulnerability aligns with the ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically the use of shell commands, and represents a critical path for privilege escalation and lateral movement within network environments.
Mitigation strategies for this vulnerability should include immediate firmware updates from TP-Link to address the command injection flaw in the affected uhttpd implementation. Organizations should also implement network segmentation to limit access to administrative interfaces and enforce strict access controls using multi-factor authentication. Network monitoring solutions should be configured to detect suspicious command execution patterns and unusual traffic to the cgi-bin/luci endpoints. Device administrators should regularly review and rotate administrative credentials, disable unnecessary services, and implement proper input validation at all levels of the application stack. Additionally, security teams should conduct regular vulnerability assessments of network infrastructure devices and establish incident response procedures for handling such critical vulnerabilities. The root cause of this issue demonstrates the importance of following secure coding practices including input validation, output encoding, and proper command construction when developing web interfaces for embedded systems. Organizations should also consider implementing web application firewalls to provide additional protection layers against similar injection attacks targeting web-based administrative interfaces.